Heat-treatment effect of dispersed particles on the preparation of thick silica films by using electrophoretic sol-gel deposition

Thick silica films with no cracks were prepared on a stainless steel sheet by electrophoretic sol-gel deposition. The sols for electrophoresis were prepared by the re-dispersion of silica particles which were separated from the original sol made from a silicon alkoxide. The sols were then heat-treated at various temperatures in air. The heat treatment of the particles, separated by centrifugation from the original sot before the electrophoresis, prevented the generation of microcracks on the surface of the films during the drying process. The maximum thickness of the as-deposited films containing no cracks was about 10 mu m when the particles were heat-treated at 600 degrees C for longer than 12 h.